Ultrasonication of Sorghum and Cowpea Slurries: Influence on Technofunctional, Rheological, and Proximate Properties

Sorghum and cowpea are African indigenous crops with significant potential to contribute to food security. However, their industrial use remains limited, partly due to challenges related to their functional and rheological properties. The aim of this study was to investigate how different ultrasonication parameters influence the technofunctional, rheological, and proximate properties of sorghum and cowpea slurries. Raw sorghum and cowpea grains were separately milled into flour, and each was mixed with distilled water at a 1:2 (w/v) flour-to-water ratio before ultrasonication treatment. The mixtures were then subjected to ultrasonication at 25%, 50%, and 75% amplitude for 30 min and 1 h. The ultrasonicated flour slurries were freeze-dried and subsequently blended into fine flour for analyses. The samples were evaluated for their color, technofunctional properties (including bulk density, water solubility index, water absorption index, swelling power, water, and oil absorption capacity), rheological behavior, and proximate composition. The results revealed that ultrasonication significantly modified the protein (10.30%-11.05% in sorghum; 23.20%-24.85% in cowpea) and fiber (0.06%-0.60% in sorghum; 2.51%-6.41% in cowpea) contents of sorghum and cowpea samples, with the extent of change dependent on the applied amplitude and treatment time. Ultrasonication at higher intensities and longer exposure times induced notable alterations in hydration characteristics, including increased water absorption capacity (1.16-1.34 g/g in sorghum and 1.49-1.59 g/g in cowpea) and water solubility index (1.26 g/100g -2.58 g/100g in sorghum), while improving viscosity and viscoelastic parameters, thereby suggesting potential for better processing functionality. Overall, the study establishes that ultrasonication is an effective green technique for modifying the technofunctional, rheological, and proximate properties of sorghum and cowpea flours.